Field of the Invention
The present invention relates to a control apparatus and a correction method.
Description of the Related Art
In recent years, research and development has been actively performed for a configuration for providing a free viewpoint video image in which a viewer can appreciate content while selecting an area he or she wishes to view. Also, a head mounted display (HMD: Head Mounted Display) of a head tracking type and a display of handheld type have been put into practical use as devices for enjoying free viewpoint video content. There are omnidirectional images, which are free viewpoint video content, that join and align a virtual space configured by CG (Computer Graphics) or the like, and images captured simultaneously by a plurality of cameras.
Meanwhile, a configuration that presents audio content corresponding to an omnidirectional moving image using headphones of a head tracking type is known (Japanese Patent Laid-Open No. 2002-171460). This method presents audio matched to the omnidirectional video image even with headphones by the convolution of a head-related transfer function (HRTF: Head-Related Transfer Function) with a sound source in accordance with a result of head tracking.
Also, as separate omnidirectional audio presentation, a method in which a plurality of speakers are arranged so as to surround a periphery of a user, as typified by surround sound, is known.
In the case of causing free viewpoint video content to be displayed on a movable display apparatus such as an HMD, there is a possibility that, if an apparatus for detecting motion of the head on which the HMD is arranged is used for a long time, real space coordinate axes and image space coordinate axes displayed in the HMD become displaced due to accumulation of error. Therefore, in a configuration using a movable display apparatus such as an HMD and a plurality of speakers whose positions are fixed, there is a problem in that coordinate axes of image space displayed in the HMD and the coordinate axes of the acoustic space of the audio output by the plurality of speakers do not necessarily match. If the coordinate axes of image space displayed in the HMD and coordinate axes of the acoustic space of the audio output by the plurality of speakers do not match, it may feel unnatural to the viewer, and cause a reduction of a realistic sensation for a reproduction of free viewpoint video content.
The present invention was conceived to solve above described problems, and an objective is to provide a technique that can match coordinate axes of an acoustic space and coordinate axes of an image space.